The present disclosure relates to the oil and gas industry and, more particularly, to determining particle size distribution in fluids using real-time ultrasound techniques.
During the drilling and production of a subterranean formation, such as a hydrocarbon-producing well, various wellbore treatment fluids are circulated in and/or out of the well. Such fluids may include, but are not limited to, drilling fluids, drill-in fluids, completion fluids, fracturing fluids, work-over fluids, and the like. These fluids used in various subterranean formation operations, may be collectively referred as “treatment fluids” (or as “wellbore fluids”). Treatment fluids often include a plurality of particles that impart specific properties (e.g., viscosity, rheology, mud weight, and the like) and capabilities (e.g., wellbore strengthening, fluid loss control, and the like) to the treatment fluid.
Prior to being conveyed downhole, a treatment fluid may be treated by adding or removing various components to obtain a predetermined treatment fluid mixture designed for optimal efficiency of the subterranean operation being performed (e.g., drilling, fracturing, and the like). Weighting agents, for example, are often added to treatment fluid to produce a desired mud weight (i.e., density). Weighting agents are particles having a specific gravity greater than the base fluid of the treatment fluid into which they are included and, therefore, are able to affect the equivalent circulating density (ECD) of the treatment fluid. During drilling operations, the ECD is often carefully monitored and controlled relative to the fracture gradient of the subterranean formation. Typically, the ECD during drilling is close to the fracture gradient without exceeding it, and when the ECD exceeds the fracture gradient, a fracture may form in the subterranean formation and drilling fluid may be lost into the formation (often referred to as lost circulation).
Due to natural tendencies, the physical characteristics of a treatment fluid mixture may change as it is introduced downhole and traverses a wellbore in a subterranean formation, which may result in a different particle size distribution (PSD) in the treatment fluid. For example, PSD may change due to the addition of fines or cuttings entrained in a drilling fluid during a drilling operation. Moreover, particles within a treatment fluid are subject to particle size attrition resulting from breaking down or otherwise being ground to smaller sizes while in wellbore. As the particle sizes change, the PSD of the treatment fluid is correspondingly altered. In other cases, treatment fluid particles of a certain size may be lost through pores defined in the wellbore wall, and thereby also alter the PSD of the treatment fluid.